1. Technical Field
This invention relates to a wheeled carriage that is arranged to transport a door or other construction panel, and to precisely position the construction panel for installation.
2. Background Art
Small hollow core doors, such as the kind commonly found in residences, can be hung by one man without particular difficulty. However, commercial doors of the kind typically found in hotels, hospitals and office buildings often weigh two hundred pounds and more. Fitting such a heavy door to its frame is a more difficult task. It ordinarily requires two men working with shims, wedges and bars to maneuver a heavy door into proper position for hanging. Workmen hanging heavy doors in that fashion are also prone to injury, particularly pinched and crushed fingers, and back strains.
The difficulties experienced in the fitting, renovation, and replacement of heavy doors and other construction panels has long been recognized and a number of dollys and trucks have been developed over the years to aid workmen in this endeavor. Examples of door handling dollys include U.S. Pat. No. 3,138,265 to Hansen; U.S. Pat. No. 3,643,935 to Bell; and U.S. Pat. No. 4,978,132 to Wilson et al. Those prior art dollys have in common a wheeled base and a frame to which a door may be secured during transport and while positioning the door to fit within an opening. The dolly that is described in the Hansen patent is arranged so that the frame holding a door panel tilts between a reclining travel position and a vertical installation position. When a door transported on the Hansen dolly is in an upright installation position, its center of mass is forward of the dolly base. In that position the dolly and door are unstable and have a tendency to tilt forward as the weight of the door and the frame is cantilevered ahead of the wheels of the base. Further, Hansen's door holding frame cannot be elevated or turned relative to the dolly base when the frame is upright; both functions being important when attempting to align a door with a mounting location.
A dolly and workbench combination is disclosed by Bell in his U.S. Pat. No. 3,643,935. The dolly includes a chassis mounted upon caster wheels, the chassis having a pair of uprights mounted thereupon. Each upright supports a tiltable beam that is arranged to support and to secure a door or other similar panel. The dolly can be used to transport a door from one place to another, and to position it for convenient mounting of hardware and hinges. Another wheeled hand truck is disclosed in the Wilson et al patent, U.S. Pat. No. 4,978,132. The truck itself is of L-shape and is arranged to securely hold a door or other panel member for transport. The truck frame can be tilted about a pair of wheels mounted to the frame adjacent the frame apex so that a door can be positioned either vertically or on its side.
The inventor's previous patent, U.S. Pat. No. 5,762,348, provided a carriage device that obviated many of the problems inherent in prior designs. That carriage provided a wheeled base to which was attached a moveable frame that was arranged to securely support a door. The frame was provided with orientation means that allowed the frame to position the door between an upright installation position and a reclined transport position. Bearing means were provided below the frame so that at least part of the weight of the door was transferred to those bearing means when the door was in its upright position, thereby avoiding the instability that was inherent in prior designs. The present invention is an improvement of the inventor's previous carriage, providing enhanced adjustability and stability when aligning a door with its mounting position.